The research aims to reveal the effect of the relationship between the mother's parental treatment styles on the adjustment to university life among the students of Sultan Qaboos University in the Sultanate of Oman, and the role played by the Big Five personality factors as a mediating variable between the mother's parental treatment styles and the adjustment of Sultan Qaboos University students to university life. The research further aims to reveal the possibility of the existence of statistically significant differences between the mother's parental treatment styles and the Big Five personality factors and the adjustment to university life among the students at Sultan Qaboos University attributed to the gender variable. The research sample amounted to (793) male and female students, who were selected using a simple stratified random method. The researcher adopted the descriptive quantitative approach and applied three measurement tools: 1) Buri's Parental Treatment Styles (Buri,1991) which is translated into Arabic and adapted to the Omani environment by (Al-Dhafri et al., 2011), and developed by Al-Kharousi et al. (2011). This independent variable consists of three dimensions: (firm, authoritarian, lenient), 2) the compatibility measurement with university life, prepared by Hajjo (2015) and adapted to the Omani environment by Alshandudi (2020), which is is the dependent variable and it consists of three dimensions: (psychological, social, school), and 3) the Big Five personality factors measurement, prepared by Abdul Khaliq (2020), which is the mediating variable and it consists of five dimensions: (extraversion, neuroticism, agreeableness, openness, mastery). The researcher used the Statistical Package for Social Sciences (SPSS) for the descriptive analysis to evaluate the validity and reliability of the data.The results and the measurement model confirmed that the model is characterized by high stability properties, as the results of convergent and discriminant validity indicated the quality of the model and that it measures what it was designed to measure. To answer the study questions and its hypotheses, path analysis and structural equation modeling (PLS-SEM) were adopted using the (SMART PLS) program. The research findings showed that the measurement of the mother's parental treatment methods had a positive significant effect on the measurement of the big five personality factors, as the value of the coefficients in all the measurements was positive and its significant P-value was less than (0.001). It also revealed that the measurement tool of the mother's parental treatment methods had a positive significant effect on university life compatibility, as the value of the coefficients in all the scales was positive and its significant P-value was less than (0.001). The findings, in addition, showed that the measurement tool of the big five personality factors, as a mediating factor, had a positive effect on university life compatibility measurement, as a dependent variable, as the value of the coefficients in all the measurements was positive and its significant P-value was less than (0.001). It is evident that there are no significant differences in the methods of parental treatment of the mother and the five major factors of personality and compatibility with university life among Sultan Qaboos University students attributed to the gender variable, as the t-value was less than (0.05). The research recommended the importance of designing training programs targeting fathers; to enlighten them about the positive and negative parental methods and their impact on children's personality patterns and their psychological, social and academic compatibility. It also recommended the necessity of preparing special programs by religious, social, psychological and educational institutions within the programs of qualifying those about to get married to carry out their future roles as fathers and mothers and to make these programs obligatory to complete the marriage contract.